W3C on Convergence
By Justin Ried, Wed Feb 28 00:00:00 GMT 2001

TheFeature had a chance to talk with the World Wide Web Consortium's Chair of the HTML Working Group, Steven Pemberton, to discuss the convergence of the wireless and wired worlds.

With the mobile community getting a taste of the mobile Internet via WAP services, many people are wondering if and when true convergence will happen. The recent announcement that WAP 2.0 (or WAP NG) would include support for XHTML Basic led many to speculate that convergence was finally at the doorstep. Will we be able to read regular Internet web pages from our mobile devices, no longer confined to the walled-gardens of WAP created by network operators? If so, when?

The World Wide Web Consortium (W3C) is the authority for developing and maintaining Internet standards such as HTML and XML. TheFeature's technology editor, Justin Ried, had a chance to talk with the W3C's Chair of the HTML working group, Steven Pemberton, to discuss these questions.

TheFeature: The WAP Forum recently announced that it was adopting XHTML Basic as a basis for WAP 2.0. What is XHTML Basic?

Pemberton: XHTML Basic is a latest in a series of planned XHTML languages. It has been explicitely designed to be suitable for small devices, such as telephones. But Basic is the first in the series to be defined with XHTML Modularization.

TheFeature: XHTML Modularization?

Pemberton: One of the aims of XML was to end the tag wars, where different browsers supported different sets of tags. XML allows you to define your own tags and attributes and add them to a language without necessarily writing a new browser. In that way, the unit of granularity of extensibility for a markup language is the tag and the attribute.

XHTML Modularization makes the unit of granularity the module, a collection of elements and attributes that you can use to plug together with other modules to make related families of languages. So for instance, we define a module for tables. Tables of what? We don't say: that is a sort of parameter to the module. You supply the parameter, and the module creates tables of those things for you.

TheFeature: How is that going to bring us closer to a lingua franca, so that regular web browsers and mobile browsers can work with the same server documents?

Pemberton: The reality is that you are always going to have divergence. Look at C-HTML, or WML, or whatever, which are there to do essentially the same thing. Modularization means that if two languages use the same module, that they will be compatible, so it reduces, though not eliminates, the problem of divergence.

TheFeature: So you think there will always be different languages?

Pemberton: Certainly, and it's not necessarily a problem either. If we can succeed in moving the semantics into a meta-level, like we have done with CSS for presentation, then it won't matter what the exact form of the markup is.

TheFeature: But won't that mean that content authors will have to author their documents several times for different devices?

Pemberton: Of course divergence of languages matters to authors, and that is why Modularization can help, by agreeing on broad details of languages; but again, if we succeed in moving the semantics into a meta-layer, browsers will be able to process many differing languages at no extra cost.

Frankly, I believe that special languages for small devices are a historical anomaly, just like special programming languages for small computers were. The Opera browser has already shown that you can handle all of HTML 4, CSS, as well as XML and WML in one fast browser that fits in an amount of memory that we shortly won't worry about.

TheFeature: What's next after XHTML Modularization?

Pemberton: Modularization was originally for us (the HTML Working Group) just a tool to help us manage the production of a series of related languages. However, judging by the number of markup languages that have started using it, and the number of schema languages that are appearing that use XHTML Modularization as a test case, it has taken on a life of its own.

We are now working on a number of new modules that meet modern requirements. Events for instance need a thorough overhaul; the Forms module has become a separate working group with all sorts of interesting requirements; and even humble text markup has accessibility shortcomings that we would like to address.

Steven Pemberton is a senior researcher at the CWI, a national research center for mathematics and computer science, in Amsterdam in the Netherlands. In addition to his duties with the W3C, he is editor-in-chief of ACM interactions.

Justin Ried keeps trying to access Slashdot.org from his Nokia 6210 through Google's WAP search translator. He's hoping he won't have to do that much longer, thanks to the hard-working people at W3C and the WAP Forum.